(a) Field due to an infinitely long straight uniformly charged wire
To calculate the electric field, consider an infinitely long straight line of charge, having linear charge density lamda. Let P be a point at a perpendicular distance 'r' from the line of charge. To find the field at P, imagine a cylinder of radius 'r' having length 'l' with its axis as line of charge. Here, the cylinder is considered as Gaussian surface. P is a point on the GAussian surface.
The electric flux through the two circular faces is zero since electric field is normal to the area vector. Electric flux through the curved surface of cylinder.
By Gauss's theorem, total flux is equal to 1/epsilon zero times the net charge enclosed by the cylindrical surface. The direction of this field is normal to the curved surface passing normally to it.
(b) Electric Field Due to Infinite Plane Sheet of Charge
Consider a plane sheet of charge of surface density sigma. Gaussian surface which is a pillbox of area of cross section A as shown. Electric flux through the curved surface of the pill box will be zero, because electric field and area vector are normal to each other.
If sigma is positive E is directed normally out of the plate and if sigma is negative E is directed normally in to the plate.
To calculate the electric field, consider an infinitely long straight line of charge, having linear charge density lamda. Let P be a point at a perpendicular distance 'r' from the line of charge. To find the field at P, imagine a cylinder of radius 'r' having length 'l' with its axis as line of charge. Here, the cylinder is considered as Gaussian surface. P is a point on the GAussian surface.
The electric flux through the two circular faces is zero since electric field is normal to the area vector. Electric flux through the curved surface of cylinder.
By Gauss's theorem, total flux is equal to 1/epsilon zero times the net charge enclosed by the cylindrical surface. The direction of this field is normal to the curved surface passing normally to it.
(b) Electric Field Due to Infinite Plane Sheet of Charge
Consider a plane sheet of charge of surface density sigma. Gaussian surface which is a pillbox of area of cross section A as shown. Electric flux through the curved surface of the pill box will be zero, because electric field and area vector are normal to each other.
If sigma is positive E is directed normally out of the plate and if sigma is negative E is directed normally in to the plate.
No comments:
Post a Comment